#include
#include
using namespace std;
const int maxn = 110;
struct Inteval{
int left, right;
}I[maxn];
bool cmp(Inteval a, Inteval b){
if (a.left != b.left)
return a.left > b.left;
else
return a.right < b.right;
}
int main(){
int n;
while (scanf("%d", &n), n != 0){
for (int i = 0; i < n; i++){
scanf("%d %d", &I[i].left, &I[i].right);
}
sort(I, I + n, cmp);
int ans = 1, lastX = I[0].left;
for (int i = 1; i < n; i++){
if (I[i].right <= lastX){
ans++;
lastX = I[i].left;
}
}
printf("%d", ans);
}
getchar();
return 0;
}
